Illustrative embodiments relate to semiconductor devices, and more particularly to a semiconductor memory device and a method of verifying multi-cycle self refresh and a test system using the method.
In general, DRAM cells store data in capacitors as a configuration of electrical charges, and the electrical charges (data) may be lost due to leakage current. Therefore, the lost data needs to be restored in the DRAM cells to prevent the data from being permanently lost, which is referred to as refresh operation.
However, DRAM cells may have different data retention characteristics. That is, some DRAM cells may have data retention times shorter than other DRAM cells. The refresh operation must therefore be performed based on the DRAM cells having the shortest data retention times, which requires more power consumption.